Support is requested for the purchase of a multi-user dedicated affinity biosensor to be used primarily by four major and three minor NIH-supported investigators in the Sol Sherry Thrombosis Research Center and the Departments of Medicine, Physiology, Biochemistry, and Microbiology of Temple University School Medicine. The instrument selected is a BIACORE 2000 instrument which detects biomolecular interactions by surface plasmon resonance and is adapted to use by multiple laboratories, since it is fully automated and can simultaneously monitor 4 samples. No such instrument is currently available in the University. Applications of the instrument by the major users will involve study of the adhesive and anticoagulant activity of kininogens (Colman), role of the urokinase receptor in trophoblast invasion (McCrae), signaling by monocytes in response to proinflammatory agonists (Mosser), and molecular interaction of coagulation factor XI (Walsh). These four users will account for 80% of the instrument time. Three minor users (Grubmeyer, Monestier, and Niewiarowski) will also benefit. A technical supervisor (Pixley) will provide expertise, training and trouble shooting and will also perform experiments in collaboration with those of two of the major users. An internal advisory committee will monitor usage. The University indicates its commitment by providing the costs of a comprehensive service contract which covers all maintenance costs. The instrument, which is not available anywhere in the University, will enhance the research program by providing flexible, state of the art technology for quantitative measurement of biomolecular interactions important in cell biology and protein chemistry.